Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems, A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as opaque touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones).
A conventional imaging capacitive proximity sensor device is typically rectangular, and configured to provide capacitive images comprising pixel values for a set of capacitive pixels. The set of capacitive pixels generally corresponds to equal-sized parts of the sensing region. These parts are usually uniformly spaced when projected onto the input surface of the capacitive proximity sensor device. Thus, the capacitive pixels are typically rectangular, laid out in a rectilinear fashion, and span a rectangular region. In this way, the relationship between the capacitive image to its capacitive pixels is similar to the relationship between a display image and the display pixels.